Electrodeless low-pressure discharge lamp

Abstract

An electrodeless low-pressure discharge lamp according to the invention is provided with a lamp vessel which is closed in a gastight manner and which has an ionizable filling. The lamp vessel has an end portion with a cavity in which an electric coil is accommodated. The cavity further contains a heat conductor which extends to outside the cavity and has a flange there with an axis, a circumference, a surface which faces away from the lamp vessel and a surface which faces the lamp vessel. A mounting member is connected to the lamp vessel and fastened against the flange. The mounting member is provided with at least one hook which points radially inwards and which cooperates with a recess in the surface of the flange which faces away from the lamp vessel. The recess issues into an axial groove at the circumference of the flange extending into the surface facing the lamp vessel. This construction renders possible a quick assembly of the mounting member with the flange.

We claim: 
     
       1. An electrodeless low-pressure discharge lamp provided with a lamp vessel (10) which has an ionizable filling, which is closed in a gastight manner, which has an end portion (12) with a cavity (11) in which an electric coil (20) is accommodated, and in which in addition a heat conductor (30) is accommodated which extends to outside the cavity and has a flange (31) there with an axis (32), a circumference (33), a surface (34) which faces away from the lamp vessel and a surface (35) which faces the lamp vessel, a mounting member (40) which is fastened to the flange (31) being connected to the lamp vessel, characterized in that the mounting member (40) is provided with at least one hook (41a) which points radially inwards and which cooperates with a recess (36a) in the surface (34) of the flange which faces away from the lamp vessel, which recess issues into an axial groove (37a) at the circumference (33) of the flange (31), which groove extends up to the surface (35) which faces the lamp vessel. 
     
     
       2. An electrodeless low-pressure discharge lamp as claimed in claim 1, characterized in that the mounting member (40) is made of an elastic material, and the flange (31) has a threshold (38a) between the recess (36a) and the axial groove (37a), the threshold of the flange and the hook (41a) of the mounting member having mutually self-locating shapes in a direction away from the axial groove towards the recess, while the threshold blocks the hook in an opposed direction. 
     
     
       3. An electrodeless low-pressure discharge lamp as claimed in claim 1, characterized in that the end portion (12) of the lamp vessel (10) is fastened to a collar (50) which has at least one projection (51a) pointing inwards, and the mounting member (40) has an axial zone (42) with a recess (43a) and with a raised step (44a) tangentially bounding said recess at an outer surface, the projection of the collar resting in the recess of the first axial zone, while the raised step of the mounting member and the projection of the collar have mutually self-locating shapes in at least one tangential direction. 
     
     
       4. An electrodeless low-pressure discharge lamp as claimed in claim 3, characterized in that at least one projection (51c) of the collar (50) and at least one raised step (44c) in the axial zone (42) of the mounting member (40) have mutually cooperating profiles (52c, 45c, respectively) which allow of an axial displacement between the collar and the mounting member. 
     
     
       5. An electrodeless low-pressure discharge lamp as claimed in claim 3, characterized in that the recess (43a) in the axial zone (42) is bounded by a tangential ridge (46) at a side which faces the lamp vessel (10), the tangential ridge (46) and the projection (51a) having mutually self-locating shapes upon a displacement of the mounting member towards the lamp vessel, while the tangential ridge blocks the projection in an opposed direction. 
     
     
       6. An electrodeless low-pressure discharge lamp as claimed in claim 3, characterized in that the mounting member has mutually adjoining axial zones (42, 42') as described in that Claim, while the raised step (44a) of a zone (42) lying farther removed from the lamp vessel axially adjoins the recess (43c') of the axial zone (42') lying closer to the lamp vessel. 
     
     
       7. An electrodeless low-pressure discharge lamp as claimed in claim 1, characterized in that the coil (20) is provided around a coil former (22) which has a widened end (23) which is clamped in between the flange (31) and the mounting member (40). 
     
     
       8. An electrodeless low-pressure discharge lamp as claimed in claim 7, characterized in that the widened end (23) of the coil former (22) supports electrical contacts (24a, 24b, 24c) for connection of the coil (20) to electrical conductors, and in that the mounting member (40) has an annular portion (48) which covers said electrical contacts. 
     
     
       9. An electrodeless low-pressure discharge lamp as claimed in claim 7, characterized in that an electrical conductor (25) is clamped in between the flange (31) and the widened end (23) of the coil former (22).